/Engine/Plugins/Experimental/PCG/Source/PCG/Public/PCGNode.h
When we create a new graph, we initialize the input/output nodes as default, with default pins. Those default pins are not serialized, therefore if we change the default pins, combined with the use of recycling objects in Unreal, can lead to pins that are garbage or even worse: valid pins but not the right one, potentially making the edges connecting wrong pins together! That is why we have a specific function to create default pins, and we have to make sure that those default pins are always created the same way.
void CreateDefaultPins ( [TFunctionRef](API\Runtime\Core\GenericPlatform\TFunctionRef)< [UPCGPin](API\Plugins\PCG\UPCGPin) *([UPCGNode](API\Plugins\PCG\UPCGNode) *)> PinAllocator )